Controlling RC Toys With The Raspi

June 3, 2014 by Brian Benchoff 18 Comments

signal

An interesting trick you can do with a a fast CPU and a GPIO pin mapped directly to memory is an FM transmitter. Just toggle a pin on and off fast enough, and you have a crude and kludgy transmitter. [Brandon] saw a few builds that turned a Raspberry Pi into an FM radio transmitter and realized a lot of toy remote control cars use a frequency in the same range a Pi can transmit at. It’s not much of a leap to realize the Pi can control these remote control cars using only a length of wire attached to a GPIO pin.

The original hack that turned a Pi GPIO pin into an FM transmitter mapped a GPIO pin to memory, cycled through that memory at about 100 MHz, and added a fractional divider to slightly adjust the frequency, turning it into an FM transmitter. Cheap RC cars usually listen for radio signals at 27 and 49 MHz. It doesn’t take much to realize commanding RC cars with a Pi is possible.

The only problem with this idea is that most RC cars use pulse modulation. For an RC transmitter to send the command for ‘forward’, a synchronization pulse is sent, then a series of pulses and pauses. The frequency doesn’t change at all, something the originally FM code doesn’t do. [Brandon] realized that if he just moved the frequency up to something the RC car wasn’t listening to, that would register as a zero.

All that was left was to figure out the command codes for his RC truck. For this, [Brandon] decided brute force would be the best option. Armed with a script and a webcam, he cycled through all possible combinations until the webcam detected a moving truck. Subtlety brilliant, if you ask us. Of course more complex commands required an oscilloscope, but now [Brandon] has a git full of all the code to control a cheap RC car with a Pi.

Bare Bones Arduino IR Receiver

May 30, 2014 by Nick Conn 7 Comments

TV Remote

Old infrared remote controls can be a great way to interface with your projects. One of [AnalysIR’s] latest blog posts goes over the simplest way to create an Arduino based IR receiver, making it easier than ever to put that old remote to good use.

Due to the popularity of their first IR receiver post, the silver bullet IR receiver, [AnalysIR] decided to write a quick post about using IR on the Arduino. The part list consists of one Arduino, two resistors, and one IR emitter. That’s right, an emitter. When an LED (IR or otherwise) is reverse biased it can act as a light sensor. The main difference when using this method is that the IR signal is not inverted as it would normally be when using a more common modulated IR receiver module. All of the Arduino code you need to get up and running is also provided. The main limitation when using this configuration, is that the remote control needs to be very close to the IR emitter in order for it to receive the signal.

What will you control with your old TV remote? It would be interesting to see this circuit hooked up so that a single IR emitter can act both as a transmitter and a receiver. Go ahead and give it a try, then let us know how it went!

A Wireless Computer Remote That Emulates A USB Keyboard

May 25, 2014 by Nick Conn 7 Comments

PCRemote

If you are anything like [Antoine], you would love to be able to control your PC with a simple hand-held remote control from anywhere in your house. [Antoine] wrote in to tell us about his wireless computer remote that emulates a USB keyboard, making it suitable for any device that uses a USB keyboard.

His blog post is very well written and contains a ton of design information and background on the project. He initially wanting to easily control his PC’s music from anywhere in his house without needing to be within line of sight of his computer. The end result is a very handy remote that can be used to change music, video, and even launch applications on his computer. The system consists of a base station for his remote that connects to the computer and acts as a USB keyboard, and the remote itself. The base station uses V-USB on an Arduino to interface with the computer, and VirtualWire to handle the wireless protocol for the remote. For those of you who don’t know about VirtualWire (now superseded by RadioHead), it is a very cool Arduino library that lets you easily use raw wireless interfaces (also called vanilla wireless interfaces).

Without going into too much detail here (be sure to see the actual post for more information), the remote itself was redesigned after the initial proof of concept to maximize battery life. The final power consumption is very impressive, resulting in a battery life of more than two years! This remote system is very well put together and contains many aspects that can easily be reused for other projects.

High Altitude Glider Will Be Dropped From A Balloon!

May 22, 2014 by James Hobson 29 Comments

[House4Hack] and [HABEX] have teamed up to design and build a glider system that can be taken up 30-40km via a weather balloon, dropped, and flown home via FPV.

Of course, this has been done before, but you know what, it’s such a cool experiment, and so few people have done it… who cares! The goal is to hit at least 20km altitude, hope for 30km, and if possible — 40km would break records. For reference, the one we linked made it 33km up.

The plane is a Mini-talon V-tail, which was donated to them by their local hobby shop as a sponsorship. It features an ArduPlane Autopilot module, a 1.2GHz video transmitter, a long range 433MHz receiver for the control signal, and a telemetry data link at 433MHz connected to the ArduPlane. Two GoPro cameras make up its eyes, and it also has a custom release mechanism for letting go of the weather balloon.

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Sealed-System Bucket Loader Cleans Messes In Dangerous Places

May 20, 2014 by Mike Szczys 23 Comments

[youtube=https://www.youtube.com/watch?v=XjHJ71SVop4&w=580]

Cleaning up after a disaster is hard and dangerous. But the ROEBL project is trying to make it substantially safer by removing the human operator from harm’s way. The Remote Operated Electric Bucket Loader had a big double-fenced, cement barrier play area set up at Maker Faire and [Justin Gray] walked us through the project which concluded with a demonstration of the hardware.

For now the operator does need to be on site to see what the loader is doing, but a first-person video setup is planned for the future. Still, removing the operator from the jarring experience of riding inside is an improvement. And the sealed nature of the electric and hydraulic systems mean that it can operate in areas inundated with liquids like water or oil.

The video above has a 90 second demonstration at the end (while we all laugh like children at what really was a giddy display of power being thrown about by a handheld controller). The ROEBL website has a gallery where you can see the conversion process that started with a standard diesel machine.

Reading 2.4GHz Transmitters With An Arduino

May 10, 2014 by Brian Benchoff 11 Comments

Quad There are a lot of cheap quadcopter kits out there, sold ready to fly with a transmitter and battery for right around $50 USD. One of the more popular of these micro quads is the V2X2 series. They are, unfortunately not compatible with any other radio protocol out there, but [Alexandre] has managed to use the transmitter included with his V202 quad to send data to an Arduino.

Like most quads, the transmitter that came with [Alexandre]’s V202 operates on 2.4GHz. Listening in on that band required a little bit of hardware, in this case a nordic Semiconductors nRF24L01p. Attached to this chip is a regular ‘ol Arduino running a bit of code that includes [Alexandre]’s V202 library.

Right now, the build can detect if the quad is bound or not, and read the current position of the throttle, yaw, pitch, and roll, as well as all the associated trims. It’s just the beginnings of [Alexandre]’s project, but his eventual goal is to build an Arduino bot based on the code, complete with RC servos. Not bad for a transmitter that will be utterly useless when the microquad eventually breaks.

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Remote Control Anything With A PS3 Controller

March 3, 2014 by Brian Benchoff 14 Comments

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When looking for a remote control for your next project, you might want to look in your living room. Wii controllers are a hacker’s favorite, but wagging an electronic wand around isn’t the greatest for remote control planes, cars, tanks, and multicopters. What you need for this is dual analog controls, something every playstation since the 90s has included.

[Marcel] created a replacement electronics board for the Sony DualShock 3 controller for just this purpose. With this board, an XBee, and an old controller, it’s easy to add dual analog control and a whole lot of buttons to any project using an XBee receiver.

The replacement board is based on the ATMega328p uC, includes a Lipo charge circuit and power supply, and inputs for the analog sticks and all the button boards inside the DualShock controller.

Yes, we have seen an earlier version of [Marcel]’s project before, but this time he’s added a few new features – the rumble now works and thanks to multiple people unable or unwilling to spin a few boards, [Marcel] has put up an Indiegogo campaign.

Video below.
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